Meta-analysis is increasingly being used in clinical research to address controversial issues where data from clinical trials are inconclusive [1, 2].

The Mantel-Haenszel test [3, 4], the most commonly used statistical technique for determining the overall odds ratio (or relative risk) of a meta-analysis, is calculated by pooling appropriately the individual odds ratios in published studies. Logistic regression [4] can also be used even though the technique is considerably more complex.